This description of pertussis outbreaks occurring in healthcare facilities and reported to the InVS aims to provide guidance on how to respond to cases of pertussis in healthcare settings. Between 2000 and 2007, 68 outbreaks were reported, 47 (69%) of which were reported as nosocomial infections. A total of 413 cases were recorded, half of which were biologically confirmed. The number of outbreaks reported each year was increasing; 78% involved clusters of cases (an average of 8 cases per outbreak), 56% involved only healthcare workers, and 28% also involved patients. An outbreak lasted an average of 37 days, and the average time between the start of the outbreak and the date of reporting was 47 days. For 84% of outbreaks, active case finding was implemented. The high proportion of reported cluster cases underscores that diagnosing pertussis is difficult and that mask-wearing alone is insufficient among those with a cough. Managing a pertussis outbreak entails significant financial and human costs. Vaccinating staff, raising awareness about wearing masks as soon as the first symptoms of a cough appear, and reporting cases immediately to the occupational physician should contribute to better control of pertussis clusters in healthcare facilities. (R.A.)